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Regarding "floating" soundboard splits a more natural woodworking type repair for the problem area Del describes would be to route a 3/8" channel directly above the rib ends of the area of the split all the way to the rim, setting the depth of cut to aprox 1/2 the board thickness and inlaying spruce tenons with the grain direction 90 degrees from the board itself. A type of inserted flush rib so to speak, that will reinforce the weak exposed portion of the board.

Mixing fiberglass cloth and spruce in just one area of the soundboard surface will leave the repair able to come loose due to differential movement between the fiberglass, (which will not move with humidity changes) and the board, (which will).

Regarding "floating" soundboard splits a more natural woodworking type repair for the problem area Del describes would be to route a 3/8" channel directly above the rib ends of the area of the split all the way to the rim, setting the depth of cut to aprox 1/2 the board thickness and inlaying spruce tenons with the grain direction 90 degrees from the board itself. A type of inserted flush rib so to speak, that will reinforce the weak exposed portion of the board.

Mixing fiberglass cloth and spruce in just one area of the soundboard surface will leave the repair able to come loose due to differential movement between the fiberglass, (which will not move with humidity changes) and the board, (which will).

It would also look like heck and would devalue the piano.

We're talking about a strip fiberglass about 1" wide—it has to be wide enough to bridge the area between the inner rim and the ends of the ribs—and, maybe, 4" to 6" long. It bridges the space between the inner rim and the end of the one rib that terminates in that area. There is all of about 1/2" of fiberglass extending over the free area of the board. With the fibers at 45° to the grain line—I’d hope biaxial cloth would be used—and a decent epoxy this cloth will follow any expansion and contraction that might occur. It is an effective and simple repair and it permanently stops any further cracking.

It does not "look like heck." Done with any kind of finesse it is a completely invisible and permanent repair. I fail to see how it could possibly devalue the piano.

In their smaller grands the ribs were terminated some short distance from the inner rim; the ribs were not set into notches cut in the inner rim.

I've wondered why ribs were inset into the rim for a long time. I just seemed like a simple and natural thing to stop them a bit short in order to create an area with higher compliance. One could almost think of this as the surround used with speakers. The surround does most of the flexing, and the cone is then designed to be stiff to that it might ideally move as a single unit. Care to comment further?

Originally Posted By: Del

The only two design features that are significantly different from other pianos of similar type and size are the vertical hitchpins... (which are good things) and the treble section termination pieces (which are a good idea poorly executed). When I rebuilt these pianos I kept both features. I like the vertical hitchpin concept but I didn’t like the original roll pins so I replaced them with solid stainless steel pins similar to those I designed into the two Walter grands.

I've looked for the type of vertical hitchpins that your Walter grands use and haven't found them in any of the usual piano-supply catalogs. Are they, in fact, available, or do you have them made?

I've wondered why ribs were inset into the rim for a long time. I just seemed like a simple and natural thing to stop them a bit short in order to create an area with higher compliance. One could almost think of this as the surround used with speakers. The surround does most of the flexing, and the cone is then designed to be stiff to that it might ideally move as a single unit. Care to comment further?

It is similar, but not quite the same. As you say, you don’t really want a speaker cone to bend or flex at all. It should act like a piston. Piano soundboard assemblies don’t quite act like this; when they are forced into motion by the vibrating strings they do—and should—bend very slightly.

They seem to work best when they bend smoothly across the span of the assembly. Almost, but not quite, like a hinged-edge vibrating panel. The only analogy that comes to mind at the moment—and it’s not a particularly good one—is that of a trampoline panel that has been stiffened in the middle and becomes more flexible as you move away from the middle. It something of a compromise between a clamped-edge vibrating panel and a hinged-edge vibrating panel; it is not a true hinged-edge system but it is also some removed from a clamped edge system. It is a system that works most efficiently when the feathering is made less abrupt and is carried further in toward the middle of the board.

I haven’t done enough direct A-B testing of the two systems to be able to prove categorically that either is acoustically superior although intuitively it would seem that terminating the ribs at a slight distance from the rim—“floating” the ribs—should have a slight edge. (Assuming the ribs are designed correctly.)

Insetting the ribs to the inner rim seems to have been at least in part a protective measure used when animal hide was the only adhesive choice around. The argument is made that animal hide glue is a very strong adhesive and it would not have been necessary to reinforce it in this way. But manufacturers were not always careful in preparing and using the stuff. Temperatures were not always well-controlled and it was used long after it should have been discarded and replaced.

As well, the process of putting a compression-forced crown into a soundboard assembly creates a lot of stress on the glue joint all by itself. Insetting them protects the integrity of the glue joint.

This is a non-issue, of course, with laminated soundboard panels.

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I've looked for the type of vertical hitchpins that your Walter grands use and haven't found them in any of the usual piano-supply catalogs. Are they, in fact, available, or do you have them made?

Those pins are made by both Driv-Loc (Type G) and Groov-Pin (Type 67). There are probably others but those are the two I’ve used in the past. For my own work I used either Driv-Loc Type H or Groov-Pin Type 24. Both of these are solid pins. They look similar but do not have the annular groove around the top. The strings can be moved up or down on the pin by a millimeter or so; I prefer that they not be more than 5 mm above the plate surface in the bass nor more than 3 mm above the plate in the treble.

I think the operative assumption about the value of a specific repair to a soundboard is-would a manufacturer do a warranty repair of the nature planned. If it is inconceivable that a manufacturer would execute a specific repair procedure- for a technician to do this for a client puts them in a less than professional light.

Also if the repair is of such unorthodoxy as to be incompatible with the overall engineering of the structure-when the piano goes on the market this will affect the value.

When pianos are of such age as to be largely devalued-different repair protocols can be appropriate.

I think the operative assumption about the value of a specific repair to a soundboard is-would a manufacturer do a warranty repair of the nature planned. If it is inconceivable that a manufacturer would execute a specific repair procedure- for a technician to do this for a client puts them in a less than professional light.

Also if the repair is of such unorthodoxy as to be incompatible with the overall engineering of the structure-when the piano goes on the market this will affect the value.

When pianos are of such age as to be largely devalued-different repair protocols can be appropriate.

Well, now the whole tone of your response is even more puzzling.

Baldwin’s typical response to this problem (on the rare occasions that it was discovered in a piano still under warrantee) was for the technician to shove some glue in there from the bottom—to keep it from getting worse—and forget about it. The specific crack under discussion can neither be seen nor accessed from the top unless the plate is removed from the piano. Indeed, it is fairly difficult to see even from the bottom of the piano unless you know specifically where to look and what to look for.

I think the operative assumption about the value of a specific repair to a soundboard is-would a manufacturer do a warranty repair of the nature planned. If it is inconceivable that a manufacturer would execute a specific repair procedure- for a technician to do this for a client puts them in a less than professional light.

Also if the repair is of such unorthodoxy as to be incompatible with the overall engineering of the structure-when the piano goes on the market this will affect the value.

When pianos are of such age as to be largely devalued-different repair protocols can be appropriate.

Hmm, I certainly wouldn't limit myself to the options the factory has. Given the wide range of approaches and failures coming out of factories, to define factory approaches as a standard -- much less the be all and end all of valid technical responses -- is more than a bit limiting in my opinion.

Part of our responsibilities as technicians is as a fiduciary. We protect the value of our clients pianos. We must be knowledgable of how value is determined in the piano market to do this.

A piano soundboard of a 5 to 40 year old artist quality grand repaired with fiberglass cloth epoxied to the surface over a crack would be a material fault that any buyer would want to be aware of. Competing sellers would use information like that to create uncertainty in the mind of any prospective purchaser of a piano like that. Anything that creates doubt reduces marketability. Those are the hard facts of business.

An SF-10 piano aspires to fit in the market as artist quality. I think any particular repair must be planned to take that into account. Others can have their opinion-I have stated mine. Good luck to you all!

Part of our responsibilities as technicians is as a fiduciary. We protect the value of our clients pianos. We must be knowledgable of how value is determined in the piano market to do this.

A piano soundboard of a 5 to 40 year old artist quality grand repaired with fiberglass cloth epoxied to the surface over a crack would be a material fault that any buyer would want to be aware of. Competing sellers would use information like that to create uncertainty in the mind of any prospective purchaser of a piano like that. Anything that creates doubt reduces marketability. Those are the hard facts of business.

An SF-10 piano aspires to fit in the market as artist quality. I think any particular repair must be planned to take that into account. Others can have their opinion-I have stated mine. Good luck to you all!

I agree with you about the fiduciary part. And I agree that the SF-10 aspires to be an artist-quality piano. But I disagree with most everything else.

Given what I know about the specific problem being discussed—one that is probably not even an issue in SF-10 or SD-10 models—the repair I described is the better repair. You can denigrate the use of relatively modern materials (or me, for that) all you want but that doesn’t change reality and it ignores the fact that epoxy and fiberglass reinforcements have been successfully used with wood assemblies and structures more than 70 years.

The material and method I described permanently solves all of the issues related to the specific problem that occasionally shows up for a specific reason in a specific area of the soundboard in specific pianos: namely the Model M, Model R and Model L; i.e., those models using “floating” ribs that terminate at specific spots on the inside curve of the rim. (Unless it’s confirmed by the technician actually looking at the piano I don’t believe this was ever an issue with the SF-10.)

I believe the best repair is the one designed to solve all aspects of a given problem; in this case one caused by a localized design defect. It should be unobtrusive, effective and permanent. It should use the best and most appropriate materials available. And it should not add to the original problem. It should not be arbitrarily limited to traditional materials especially if there is reason to believe that using traditional materials results in a repair that will not perform as well. The process I have suggested meets these criteria and I’m not at all convinced that the repair you have suggested will perform as well. The method you’ve suggested does use wood but wood, while “traditional,” is not always the best choice.

Del; whether wood is or is not the "best" choice to repair a soundboard defect -that you have perfectly described-wood IS what the soundboard is engineered to be made from. Departing from that creates a "known, un-known" future. Using cross-ply, wood, to restrain splitting is part of the original engineering of the soundboard. Just like a rib does. If you read anything into my words implying that I seek to "denigrate you", please accept my apologies. Don't we know each-other well enough to stay calm? Sincerely, Ed

whether wood is or is not the "best" choice to repair a soundboard defect -that you have perfectly described-wood IS what the soundboard is engineered to be made from.

To me, this is not compelling logic. Wood is indeed what the soundboard was made from (not because it is the ideal material but because it has been the best available material). And wood is what failed. It may be that the design or execution failed to account for the weakness of wood, but wood is what failed, is it not?

If, then, wood is what failed, is it not legitimate to consider alternative materials?

Quote:

Departing from that creates a "known, un-known" future. Using cross-ply, wood, to restrain splitting is part of the original engineering of the soundboard.

I'm not buying this at all. Those of us who know wood (certainly including any experienced piano technician) know that any given piece of wood is an "unknown". Nobody on the planet can predict the response of any given piece of wood. Not even if they have access to MRI and x-ray equipment. So, using wood in a repair --or new construction, for that matter-- always contains an element of the unknown, just because it's wood.

And, lamination of fiberglas/epoxy type materials to wood is very much of a "known" process. Individual piano technicians may not know, but the boat industry has been doing it for years -- both in brand new construction and in repairs of classic wooden boats.

I just don't see that the case is made not to use the repair Del described -- even as a first option.

The wood "failed" because of an engineering defect. The engineering of successful, durable, modern soundboards is a well established procedure at least 150 years old.The fact that fiberglass over wood boats have been made for some 60 years does not make it a known piano application. That makes it a known, un-known. The uncertainty is obvious. It is a piano-not a boat. Respectfully yours, Ed

The wood "failed" because of an engineering defect. The engineering of successful, durable, modern soundboards is a well established procedure at least 150 years old.

I dunno . . . Soundboard failure is not a novel event. I see soundboards all the time that have failed . . .

And, I believe I have a fair grasp of those techniques since I have been replacing 'em since the '70s.

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The fact that fiberglass over wood boats have been made for some 60 years does not make it a known piano application. That makes it a known, un-known. The uncertainty is obvious. It is a piano-not a boat. Respectfully yours, Ed

Again, most of the soundboard failures I see are because soundboards are made of wood . . .

But the idea you present is similar to some of what is being said about non-wood action components -- based on the assumption that the laws of chemistry and physics are not uniformly applicable across the spectrum of substances and events but that they are somehow suspended at the border of "piano work". The scientific approach makes the assumption that phenomena are repeatable and applicable in different parts of the world and in different applications.

Simply put, wood and fiberglas construction is wood and fiberglas construction. Period. And, they are known and understood. The properties of that kind of construction can be expected to manifest the same performance characteristics regardless of its application.

Certainly, being exposed in other applications to stresses greater than what would be normal for a soundboard would be encouraging to the idea that application in soundboard construction is a valid consideration.

The wood "failed" because of an engineering defect. The engineering of successful, durable, modern soundboards is a well established procedure at least 150 years old.

And the repair I outlined is designed to both repair the damage resulting from that engineering defect and protect the soundboard from further damage.

Quote:

The fact that fiberglass over wood boats have been made for some 60 years does not make it a known piano application. That makes it a known, un-known. The uncertainty is obvious. It is a piano-not a boat.

Mr Akin;Again thank you for your interest and I must say I am flattered by you using the reference to the "constancy" rule of Physics. I have used that in many of my lectures to Technicians. Perhaps you attended one?

The particular failure described in this thread is rooted in a wood engineering fault.

I use W,N,&G composite shanks on most of my action rebuilds so I am not new material adverse.

Del and Mr Akins;You both return to the "boat" theory of soundboard construction. You both make new soundboards for pianos. Have you ever made one for a retail client that had fiberglass coated to the top surface?

I can confidently predict that a soundboard made of solid spruce with ribs on the bottom, (with the usual dimensions), and fiberglass on the top would not function well. It would be too heavy. I know of no fiberglass cloth available with fine enough fiber size and weave to attempt such a construction. I don't think that carbon fiber is light enough either.

Using this technique on a portion of the top for a spot repair would carry the uncertainty of whether the reaction of the board to humidity changes might lead to separation between the glass and board. It would also look out of place and this is no small matter when evaluating a pianos marketability.

My repair technique is consistent with the engineering of piano soundboards thus it carries no risk beyond the workmanship.

I remember the beaches of the area of Puget Sound where I grew up as having been littered at times with plywood boats that were glassed on the outer surface only. The moisture caused the glass to separate from the wood in only a few years.

Neither of you has made a case for glassing over a cracked soundboard. The application of new methods to pianos is something I am always on the lookout for. But I am also very conservative on how I test these. Thats the responsible way. Thanks for listening and good luck!

You both return to the "boat" theory of soundboard construction. You both make new soundboards for pianos. Have you ever made one for a retail client that had fiberglass coated to the top surface?

I can confidently predict that a soundboard made of solid spruce with ribs on the bottom, (with the usual dimensions), and fiberglass on the top would not function well. It would be too heavy. I know of no fiberglass cloth available with fine enough fiber size and weave to attempt such a construction. I don't think that carbon fiber is light enough either.

Using this technique on a portion of the top for a spot repair would carry the uncertainty of whether the reaction of the board to humidity changes might lead to separation between the glass and board. It would also look out of place and this is no small matter when evaluating a pianos marketability.

My repair technique is consistent with the engineering of piano soundboards thus it carries no risk beyond the workmanship.

I remember the beaches of the area of Puget Sound where I grew up as having been littered at times with plywood boats that were glassed on the outer surface only. The moisture caused the glass to separate from the wood in only a few years.

Neither of you has made a case for glassing over a cracked soundboard. The application of new methods to pianos is something I am always on the lookout for. But I am also very conservative on how I test these. Thats the responsible way. Thanks for listening and good luck!

And you have not made a convincing argument for rejecting this repair.

You are stretching the nature of the repair I described beyond all recognition. The key words in the above are “spot repair.” This is a spot repair to a specific area and type of damage. Typically this is a shear crack immediately adjacent to inside treble curve of the inner rim—in some cases the crack may actually overlap the inner rim slightly—and is between 100 and 200 mm long. The strip of fiberglass cloth used for the repair would be approximately 25 mm wide and extend beyond the ends of the crack by about 10 to 15 mm. Much of this strip will overlap the inner rim. The rest will extend into the working area of the soundboard panel by (maybe) 30 to 40 mm at the ends. If that far. I fail to see how a strip of e-glass this size is going to weigh down the soundboard panel no matter how thick it is. Or stiffen it, for that.

You keep bringing up appearance as an issue; have you ever actually worked with this stuff? I have—although not for this specific application—and the repair, done with reasonable skill, will be virtually invisible. Sanded and finished along with the rest of the soundboard panel even your critical eye would have a very difficult time picking it out. If fact, I’m reasonably confident that if you were not told it was there and where to look you would not see it at all. Can you say the same for the repair you’ve recommended? No, I thought not.

I too have seen wood boats with fiberglass sheathing that has failed. Without exception the fiberglass was bonded to the wood hull using polyester resins, not epoxy. Polyester resins work well to bind fiberglass fibers together in all fiberglass hulls but it is not a good adhesive. So, yes, it fails when used this way. Contrast these with the many hulls I’ve looked at—we were thinking of having it done to our old wooden boat (we ended up selling the boat instead)—that were properly prepared and then sheathed with fiberglass cloth embedded in suitable epoxy resins.

When done properly this technique improves the performance of the boat, extends its useful life while reducing its periodic maintenance requirements. All materials have to be applied in a manner appropriate to the intended use.

The specific crack under discussion can neither be seen nor accessed from the top unless the plate is removed from the piano. Indeed, it is fairly difficult to see even from the bottom of the piano unless you know specifically where to look and what to look for.

and then, later,

Originally Posted By: Del

Typically this is a shear crack immediately adjacent to inside treble curve of the inner rim—in some cases the crack may actually overlap the inner rim slightly—and is between 100 and 200 mm long. The strip of fiberglass cloth used for the repair would be approximately 25 mm wide and extend beyond the ends of the crack by about 10 to 15 mm. Much of this strip will overlap the inner rim. The rest will extend into the working area of the soundboard panel by (maybe) 30 to 40 mm at the ends.

Do I understand correctly that your proposed repair is done to the top surface of the soundboard? (How else would it overlap the inner rim?) Do I therefore also understand correctly, by the part I quoted first, that when the plate is back in the piano, the repair is invisible anyway?

Do I understand correctly that your proposed repair is done to the top surface of the soundboard? (How else would it overlap the inner rim?) Do I therefore also understand correctly...that when the plate is back in the piano, the repair is invisible anyway?

That is correct. It is completely covered by the string frame. And that explains why this specific crack can be present for years—decades—and not be noticed. That, and the fact that there is rarely any audible clue drawing our attention to it.

Still, if we're going to repair something it should be done in a neat, workmanlike manner and be as unobtrusive as is practical. By being essentially invisible the repair I suggested fulfills that requirement nicely.

Del;I am convinced that most piano soundboards are made of wood. I am also convinced that the owner of such a piano wants any repairs due to engineering defects-to be engineered to work with the wood structure in a way that solves the defective design. I am also convinced that said repair should not carry any added uncertainty by introducing unknown factors into evaluating the future utility of the piano.

You are not convinced that repairing an engineering defect, that is due to the lack of an area of a soundboard having adequate cross grain restraint, with a proven piano woodworking technique is better than treating the repair area like a nautical vehicle.

So there we stand. It would be interesting to see what piano dealers think of the comparison.

Del;I am convinced that most piano soundboards are made of wood. I am also convinced that the owner of such a piano wants any repairs due to engineering defects-to be engineered to work with the wood structure in a way that solves the defective design. I am also convinced that said repair should not carry any added uncertainty by introducing unknown factors into evaluating the future utility of the piano.

You are not convinced that repairing an engineering defect, that is due to the lack of an area of a soundboard having adequate cross grain restraint, with a proven piano woodworking technique is better than treating the repair area like a nautical vehicle.

So there we stand. It would be interesting to see what piano dealers think of the comparison.

I doubt many, if any, dealers have ever encountered the problem since most of these cracks go undetected until—and for some other reason entirely—the string frame is removed from the piano. And then I suspect that most of them will want it repaired in the fastest and cheapest method possible. And that won’t be either of those we’ve been discussing.

Thanks Del;I'm so old fashioned that I still live by the old adage about a boat being a hole in the water into which you pour money! So I don't own one!

That, ultimately, was the conclusion we came to also so we sold it. It was a lot of fun while we had it, though.

ddf

There used to be an America's Cup winner in our marina here in town. I understand that when someone asked the owner what it was like to own an Americ's Cup winner, he replied, " Imagine standing in a cold shower tearing up hundred dollar bills".

The epoxy glassing of a boat hull only reduces the weight by stopping the water from soaking into the wood. So it is heavier in dry-dock but lighter on the water. Thats what counts though.

Just because glassing wood is a proven boatbuilding protocol does not mean it is proven in pianos. Introducing new materials into a piano is fraught with difficulties. Piano owners expect a long service life to a well maintained piano. 50 to 100 years is easily attainable. the new composite action parts are nearly indestructible compared to wood parts. Of course the cushioning materials will still wear and distort.

I don't know of any technician who has repaired a soundboard split with glass/epoxy overlay.

My typical client is someone with an engineering/science/technology professional-they would not find a soundboard repair with epoxy/glass to be proper.